Exam 1

Question 1

What is the Law of Composition?

Answer 1

Pure substances will contain the same elements in the same mass

Question 2

The law of constant composition applies to

Answer 2

compounds

Question 3

Define a pure substance

Answer 3

Elements and compounds

Question 4

Define heterogeneous mixture

Answer 4

Different composition, properties, and appearance throughout

Question 5

Define homogeneous mixture

Answer 5

Uniform throughout

Question 6

A combination of sand, salt, and water is an example of a ____ mixture

Answer 6

Heterogeneous

Question 7

A small amount of powdered chocolate and sugar completely dissolve in water is an example of _____

Answer 7

A homogeneous mixture

Question 8

True or false homogeneous mixtures are not easily separated into its components

Answer 8

False.

Question 9

Define physical change

Answer 9

Change to appearance

Question 10

Define chemical change

Answer 10

Transformation of a substance into a chemically different substance

Question 11

Define extensive property

Answer 11

Depends on the amount of a substance

Question 12

What are the examples of an extensive property?

Answer 12

Mass, Volume

Question 13

Define intensive property

Answer 13

Does not depend on the amount of a substance

Question 14

What are the examples of an intensive property?

Answer 14

Density, temperature, melting point, boiling point

Question 15

Of the following which is not an example of a chemical reaction?

• dissolution of penny in nitric acid
• condensation of water vapor
• a burning candle
• the formation of polyethylene from ethylene
• the rusting of iron

Answer 15

Condensation of water vapor

Question 16

Which of the following is not an intensive property?

• density
• temperature
• melting point
• mass
• boiling point

Answer 16

Mass

Question 17

Which of the following describes an extensive property?

• melts at 403 K
• density is 1.04 g/mL
• red in color
• is 2.14 moles of mlcs
• boils at 410 K

Answer 17

Is 2.14 moles of molecules

Question 18

The unit of force in English system is lb*ft/s^2, what is the SI unit for it

Answer 18

kg*m/s^2

Question 19

What are the SI units and they’re measurements?

Answer 19

G       10^9
M       10^6
k        10^3
base    1
d        10^-1
c        10^-2
m       10^-3
mu     10^-6
n        10^-9
p        10^-12
f         10^-15

Question 20

What is the formula for density?

Answer 20

d=Mass/Volume

Question 21

What is the SI unit for velocity?

Answer 21

m/s

Question 22

What is the symbol for the element sodium?

Answer 22

Na

Question 23

What are the postulates of Dalton’s atomic theory?

Answer 23

• All atoms of a given element are identical; the atoms of different elements are different and have different properties
• Atoms of an element are not changed into different types of atoms by chemical reactions;atoms are neither created nor destroyed
• Compounds are formed when atoms of more than one elmt combine; a given cmpd always has the same relative number of atoms
• Each element is composed of atoms

Question 24

Which of the following is not a chemical change?

• CO2 is produced by the combustion of gasoline
• Plants make sugar from CO2 and H20
• Dissolution of a penny in nitric acid
• The rusting of iron
• A goldsmith melts a nugget of gold and pulls it into a wire.

Answer 24

A goldsmith melts a nugget of gold and pulls it into a wire.

Question 25

Define accuracy

Answer 25

Proximity to the actual value

Question 26

Define precision

Answer 26

Proximity to obtained values

Question 27

What is the law of multiple proportions?

Answer 27

If 2 elements form more than one compound, the masses of B combine with A in a ratio of small numbers

Question 28

Rank the subatomic particles based on size and weight:

Answer 28

weight: neutrons>protons>electrons size: protons

Question 29

Isotopes are atoms that have the same ___ but differing ___

Answer 29

Atomic numbers, mass numbers

Question 30

How do you find the number of neutrons?

Answer 30

Atomic mass-atomic number

Question 31

How do you find the number of protons?

Answer 31

The atomic number

Question 32

How do you find the number of electrons?

Answer 32

The number of protons +/- charge

Question 33

How do you determine a pair of isotopes?

Answer 33

Look for the same atomic number with different masses

Question 34

How do you determine an empirical formula?

Answer 34

Divide by a common factor to the completely simplified version

Question 35

How do you know if elements will have similar properties?

Answer 35

Elements in the same column/part of the same family

Question 36

An element in the lower left corner of the periodic table is

Answer 36

definitely a metal

Question 37

When is something an ionic compound?

Answer 37

metal +nonmetal | Left+right

Question 38

When is something a covalent compound?

Answer 38

nonmetal+nonmetal | right+right

Question 39

How do you find the percentage by mass of an element in a compound?

Answer 39

1. Find the formula weight | 2. Divide the desired element by the formula weight.

Question 40

How do you determine the empirical formula of two given percentages of elements?

Answer 40

1. Convert each one to moles 2. Determine which is the limiting reagent (The smaller one) 3. Divide the answers from part 1 by the limiting reagent. 4. Write empirical formula

Question 41

What is a combination reaction?

Answer 41

A+B----> AB

Question 42

What is a decomposition reaction?

Answer 42

AB------>A+B

Question 43

What is a combustion reaction?

Answer 43

A+O2--------> CO2+H2O

Question 44

When a hydrocarbon burns in air, what component of air reacts?

Answer 44

Oxygen

Question 45

How do you find formula weight?

Answer 45

Add up the weights of each element multiplied by the amount of each element.

Question 46

How do you find the number of molecules of a compound?

Answer 46

Convert g-->mol | mol--->mlcs =avogadro's